Lately, at a lot of on ramps to interstate 75 here in North Dallas, I have seen the state's emissions spot check truck set up. They set some sensors on either side of the on ramp and somehow measure the amount of emissions of vehicles as they pass between the sensors (I assume they measure opacity somehow).
My question is this: Does anyone know if they are just taking readings, or do they have the ability to take a picture of a vehicle's license plate and send them a letter/fine if they are outside the legal limits for pollution?

Thanks,
~Rob

 

The ones I have seen around here have a camera set up as well, so I assume that if their equipment tells them your truck smokes too much then they take a picture of your plate and send you some kind of warning letter.

I've been tempted to drive by them at WOT with no boost and fill their sensors with black smoke, but I'm not so sure that's a good idea.

 

I have thought the same thing.

 

I like to confuse them by turning the engine off and coasting past them.

As for how they work, they are using a spectrograph to determine what chemicals are in the exhaust and in what concentration. I've seen the cameras, so obviously they're looking at plates, but I think their tests have as much to do with determining air quality in general in NTX as with individual emissions.

Tad

 

They have had those in the Houston area for years. What I was told is:
If your vehicle registers over the limit for some pollutant you get a letter in the mail saying you have to be SMOG checked before you can renew you plates.

 

I enjoyed seeing those when I was there... I romped on it as I went by. Let 'em send me a "smog check" letter... I keep my truck registered in NH!

Childish, I know.